Arthritic and artificial joints are subject to wear. Analysis of aspirated synovial fluid appears to be a promising method with which to study the rates, mechanisms, and biological responses to wear in human joints. Recently this institution, in cooperation with Foxboro/Trans-Sonics, Inc., has employed Ferrography to separate and recover particulate wear material from synovial fluid. Ferrography is a novel technique developed for the orderly recovery of particles from industrial lubricants. Bichromatic, polarized, and scanning electron microscopy permit identification and characterization of these wear particles. By these methods, highly characteristic particles of osseous, cartilaginous, metallic, polyethylene and acrylic materials have been identified and studied in our laboratories. Particle morphology and size appear to be related to the mode of wear of the articulating surfaces. The biological responses to these peculiar wear particles may be assessed by cytological examination of the aspirated fluid. Biochemical study of the cartilaginous wear particles may provide further insight into the etiology and pathogenesis of degenerative arthritis. Analysis of wear in arthritic and artificial joint, employing the above techniques is proposed. Attention will be directed at factors influencing wear and the pathological response to wear. The development of an objective, reliable, non-surgical wear test for these joints is anticipated. Application of this test would augment the understanding of degenerative arthritis. In addition, these techniques would permit ongoing assessment of the wear status of any implanted joint replacement. This ability to monitor current operating conditions in joints provides non-invasive assessment of implant wear and the patient's response to wear. These techniques will assist in the development and production of improved materials and designs for artificial joint implants.